1. Field of the Invention
The present invention relates to liquid crystal display devices and, in particular, to a liquid crystal display device having so-called horizontally long picture element electrodes.
2. Description of the Related Art
Conventionally, liquid crystal display devices and, in particular, active-matrix liquid crystal display devices have been widely used as display devices.
Such an active-matrix liquid crystal display device has picture elements respectively provided with switching elements, and the switching elements are controlled by providing a plurality of scanning signal lines and a plurality of video signal lines intersecting with each other. The switching elements are provided at points of intersection between the scanning signal lines and the video signal lines, and picture element electrodes connected to the switching elements are provided in such a way as to correspond to the picture elements, respectively.
(Alignment Modes)
There have been proposed various modes of alignment of liquid crystal molecules in such a liquid crystal display device. The following describes the modes of alignment of liquid crystal molecules.
Examples of the various alignment modes proposed so far include: the TN (twisted nematic) mode, in which liquid crystal molecules are twisted approximately 90 degrees; the VA (vertical alignment) mode, in which liquid crystal molecules are aligned nearly vertically to a substrate; and the like.
In particular, such a liquid crystal display device of the VA mode or the like may be provided with alignment controlling parts for controlling which direction the liquid crystal molecules are aligned along. The following gives an explanation with reference to FIG. 12. FIG. 12 is a cross-sectional view schematically showing the configuration of a liquid crystal display device.
For example, in such a liquid crystal display device of the VA mode, each picture element may be provided with a plurality of alignment regions, i.e. multiple domains, for improving viewing angle dependency. Moreover, the multiple domains may be formed by providing projections or notches cut in the pixels. The following gives a specific explanation.
That is, as shown in FIG. 12, a liquid crystal display device 10 includes a first substrate 22, a second substrate 24 opposed to the first substrate 22, and a liquid crystal material 28 sandwiched between the first substrate 22 and the second substrate 24. Provided on the first substrate 22 is an insulating film 70. Provided on the insulating film 70 are picture element electrodes 60. Provided on the picture element electrodes 60 is an alignment film 112.
On the other hand, the second substrate 24 is provided with a common electrode 90 serving as a counter electrode, as well as a color filter (not shown) and a black matrix (not shown). Further provided on the common electrode 90 is an alignment film 114.
In the liquid crystal display device 10 of FIG. 12, the second substrate 24 is provided with ribs (rivets) 100a serving as such alignment control parts 100 as mentioned above.
Each of the ribs 100a, which are projections provided on the second substrate 24, has a truncated conical shape. FIG. 12 shows a region corresponding substantially to a single picture element 14, and each picture element 14 is provided with such an alignment control part 100 as mentioned above.
As for a liquid crystal display device provided with such alignment control parts 100 as mentioned above, a technique for providing a rib in a center section of each subpixel (sub-picture element) is disclosed, for example, in Patent Literature 1.